Add AGORA subgrid model
This branch contains a new subgrid model : AGORA (--with-subgrid=AGORA) :
Pressure floor : GEAR Entropy floor : none Cooling function : Grackle 0 Chemistry : AGORA Tracers : none Stellar model : GEAR Star formation model : GEAR Star feedback model : AGORA Sink particle model : none Black holes model : none Radiative transfer : none Extra i/o : none
The details of the models are the ones used by the AGORA consortium and describted in Kim 2014, Kim 2016, Roca-Fàbrega 2021